28621440 has 96 divisors (see below), whose sum is σ = 98853300. Its totient is φ = 7630848.

The previous prime is 28621427. The next prime is 28621447. The reversal of 28621440 is 4412682.

It can be written as a sum of positive squares in 2 ways, for example, as 27123264 + 1498176 = 5208^2 + 1224^2 .

It is a tau number, because it is divible by the number of its divisors (96).

It is not an unprimeable number, because it can be changed into a prime (28621447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3276 + ... + 8244.

Almost surely, 2^28621440 is an apocalyptic number.

28621440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28621440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49426650).

28621440 is an abundant number, since it is smaller than the sum of its proper divisors (70231860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28621440 is a wasteful number, since it uses less digits than its factorization.

28621440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4994 (or 4979 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 28621440 is about 5349.9009336622. The cubic root of 28621440 is about 305.8889767680. Note that the first 3 decimals are identical.

The spelling of 28621440 in words is "twenty-eight million, six hundred twenty-one thousand, four hundred forty".